This invention relates to flexible polyurethane foams, more particularly to flexible polyurethane foams which exhibit excellent flame resistance in small scale burn testing.
Flexible polyurethane foams are widely used as cushioning material in, for example, furniture, automobile seating, impact-reducing media, and the like. One concern regarding the use of these foams is their performance under fire conditions, particularly their ability to resist igniting and to extinguish themselves when exposed to flame.
Many attempts have been made to reduce the flammability of polyurethane foam. The most common method is to incorporate a halogenated compound or phosphate ester flame retarding agent into the foam formulation. These agents have been somewhat successful in reducing the flammability of the foams. However, the use of these flame retarding agents has several substantial drawbacks. Although they are somewhat successful in suppressing flames, under fire conditions they decompose to form toxic gases, particularly gaseous halogen-containing compounds such as HCl and HBr. Foams containing these agents, although they resist flames, sometimes smolder during fires. In preparing the foam, the halogenated flame retarding agents often scorch the interior of the foam, which is believed to cause degradation of the foam properties. In addition, these flame retardant deactivate many of the catalysts used in the foam formulation. Moreover, many companies do not like to introduce halogenated compounds into the workplace for fear of worker exposure. In addition, relatively large quantities of these agents must be used in order to obtain satisfactory results, adding significantly to the cost of the foam.
Due to the drawbacks of the halogenated and phosphate ester flame retarding additive, it would be desirable to provide a polyurethane foam containing a flame retarding additive which does not release halogen-containing gases when burned, and which does not present the processing and exposure problems associated with the halogenated and phosphate ester agents.